PtCo-based nanocatalyst for oxygen reduction reaction:Recent highlights on synthesis strategy and catalytic mechanism

Oxygen reduction reaction over Pt-based catalyst is one of the most significant cathode reactions in fuel cells.However,low reserves and high price of Pt have motivated researchers worldwide seeking enhanced utilization efficiency and durability by doping non-noble metals to form Pt-based alloy catalysts.Alloying Pt with Co has been recognized as one of the most effective approaches to achieve this goal.PtCo bimetal combination is one of the most promising candidates to synthesize highly efficient catalysts for oxygen reduction reaction(ORR)applications,owing to its relatively more suitable oxygen binding energy for four-electron transfer reactions.Recently,impressive strategies have been developed to fabricate more active and stable PtCo-based multimetallic alloys with tailorable size and morphology.This paper aims to summarize the most recent highlights on the study of the relationship between preparation strategies,morphologies,electroactivities of the PtCo-based catalyst at atomic level and further the relevant reaction mechanism.The challenges and opportunities on the further development of electrocatalysts for fuel cells are included to provide reference for the practical application.

Synthesis of PtCu-based nanocatalysts:Fundamentals and emerging challenges in energy conversion

Proton exchange membrane fuel cell and direct methanol fuel cells have gained more attention due to high-energy density,remarkable conversion efficiency,and low emission.However,their widely practical application was hindered by the high usage,limited sources,and high price of Pt catalysts.To achieve more cost-effective catalytic systems,PtCu-based multi-metallic nanoparticles are highly efficient for the oxygen reduction reaction(ORR)and methanol oxidation reaction(MOR).The incorporation of non-noble Cu metal can alter the properties of hybrids by forming new facets,planes,edges to promote the cleavage or formation of chemical bonds in catalytic reaction.This is a rapid growing area with numerous contributions from the interdisciplinary areas of nanocatalysis.This paper has summarized the recent progress in the past two years,in synthesizing PtCu-based alloys with various composition and morphologies,and critically discussed the effect of the catalyst preparation method,metal precursor,surfactant,reductant and heating temperature on nanostructure and electronic configuration.The important role of the composition,size,and morphology of PtCu bimetallic catalysts for electro oxidation reactions has been further established for structure-dependency studies.The challenges and perspectives of nanocatalysts for ORR and MOR discussed in this work is to provide further insights into rational design for cost-effective materials for energy.

Highly dispersed metal incorporated hexagonal mesoporous silicates for catalytic cyclohexanone oxidation to adipic acid

Adipic acid is a dicarboxylic acid of great industrial importance,mainly used in the production of nylon-6,6 and polyurethane.The use of nitric acid as an oxidant in the industrial production of adipic acid poses significant carbon footprint to the environment.Clean adipic acid synthesis methods using a heterogeneous catalyst with H2O2 as oxidant and water as solvent have potential advantages of low catalyst cost,easy synthesis and recovery,cleanness and environmental protection.In this work,hexagonal mesoporous silicate materials were synthesized by a sol–gel method and evaluated for cyclohexanol/cyclohexanone oxidation to adipic acid.The physical and chemical properties of Fe-HMS were characterized by XRD,HR-TEM,BET and UV–Vis.The experimental results showed that Fe-HMS materials show pore sizes ranging from 2–3 nm.W-and Mo-based polyoxometalates were also evaluated and compared to the Fe-based HMS catalysts.To improve the adipic acid yield,the influence of the transition metal as well as the effect of metal loading,reaction temperature and catalyst amount on the catalytic performances of Fe-HMS have been investigated in details.When Si/Fe atomic ratio=100,Fe-HMS catalyst shows the highest activity,with a cyclohexanone conversion of 92.3%and adipic acid selectivity of 29.4%.The reaction pathway of cyclohexanone oxidation was further proposed based on experimental data.

Analysis and Zoning on Vulnerability of the Lightning Disaster in Guizhou Province

[ Objective] The research aimed to evaluate vulnerability of the lightning disaster in Guizhou and conduct zoning. [ Method] According to data of the lightning monitoring network and statistical data of the lightning disaster in Guizhou during 2007 -2012, by combining economy and population situations in 9 cities of Guizhou, 6 indicators were used to assess vulnerability of the lightning disasterCG lightning intensity, strong CG lightning intensity, annual average occurrence frequency of the lightning disaster, GDP per capita, population intensity and casualties frequency. By constructing principal component, determining weighing and comprehensive assessment, vulnerability grade of the lightning disaster in Guizhou was divided. [ Result] Guiyang was extremely high vulnerability zone, high vulnerability zone included Zunyi, Bijie and Liupanshui, moderate vulnerabili- ty zone included Anshun, Tongren and Qianxinan, Qiannan was low vulnerability zone, and Qiandongnan was extremely low vulnerability zone. Vulnerability distribution boundary of the lightning disaster in Guizhou was along northeast to southwest, and vulnerability of the lightning disaster gradually weakened from northwest to southeast. [ Conclusion] The research provided scientific basis for preventing lightning disaster and reducing damage of the lightning disaster.

Cross-metathesis of biomass to olefins:Molecular catalysis bridging the gap between fossil and bio-energy

Terminal olefins are important building blocks for the industry of biofuels,oligomers,and lubricants production.The industrial processes for production of olefins involving oligomerization of ethylene or cracking of petrochemical waxes have several flaws including low yield and high cost in product separation.Cross-metathesis of bio-derived unsaturated fatty esters and olefins with ethylene(ethenolysis),allows the conversion of sustainable waste biomass to various renewable olefins with much safer,less toxic,sustainable,and zero-CO_(2) emission processes.To our best knowledge,however,a comprehensive summary of key advances in this field(since 2017)is yet to be available,particularly on molecular features of homogeneous and heterogeneous catalysts.This paper presents a critical review on molecular structures of metal complex and oxide catalysts for ethenolysis of olefins and oleochemicals.The influence of cationic centers,coordination conditions,nature of ligands,operating conditions on catalyst performances will be systematically discussed along with relevant reaction mechanism.The key challenges for rational design of coordinated cationic hybrids have been summarized,which will provide insights to technological advancement of large-scale production of oleochemical-derived olefins.

Tau Accumulation in the Spinal Cord Contributes to Chronic Inflammatory Pain by Upregulation of IL-1βand BDNF

Microtubule-associated protein Tau is responsible for the stabilization of neuronal microtubules under normal physiological conditions.Much attention has been focused on Tau’s contribution to cognition,but little research has explored its role in emotions such as pain,anxiety,and depression.In the current study,we found a significant increase in the levels of p-Tau(Thr231),total Tau,IL-1β,and brain-derived neurotrophic factor(BDNF)on day 7 after complete Freund's adjuvant(CFA)injection;they were present in the vast majority of neurons in the spinal dorsal horn.Microinjection of Mapt-shRNA recombinant adeno-associated virus into the spinal dorsal cord alleviated CFA-induced inflammatory pain and inhibited CFA-induced IL-1βand BDNF upregulation.Importantly,Tau overexpression was sufficient to induce hyperalgesia by increasing the expression of IL-1βand BDNF.Furthermore,the activation of glycogen synthase kinase 3 beta partly contributed to Tau accumulation.These findings suggest that Tau in the dorsal horn could be a promising target for chronic inflammatory pain therapy.

Specific Regulation of m^(6)A by SRSF7 Promotes the Progression of Glioblastoma

Serine/arginine-rich splicing factor 7(SRSF7),a known splicing factor,has been revealed to play oncogenic roles in multiple cancers.However,the mechanisms underlying its oncogenic roles have not been well addressed.Here,based on N6-methyladenosine(m^(6)A)co-methylation network analysis across diverse cell lines,we find that the gene expression of SRSF7 is positively correlated with glioblastoma(GBM)cell-specific m^(6)A methylation.We then indicate that SRSF7 is a novel m^(6)A regulator,which specifically facilitates the m^(6)A methylation near its binding sites on the mRNAs involved in cell proliferation and migration,through recruiting the methyltransferase complex.Moreover,SRSF7 promotes the proliferation and migration of GBM cells largely dependent on the presence of the m^(6)A methyltransferase.The two m^(6)A sites on the mRNA for PDZ-binding kinase(PBK)are regulated by SRSF7 and partially mediate the effects of SRSF7 in GBM cells through recognition by insulin-like growth factor 2 mRNA-binding protein 2(IGF2BP2).Together,our discovery reveals a novel role of SRSF7 in regulating m^(6)A and validates the presence and functional importance of temporal-and spatial-specific regulation of m^(6)A mediated by RNA-binding proteins(RBPs).

Lipocalin 2 in the Paraventricular Thalamic Nucleus Contributes to DSS-Induced Depressive-Like Behaviors

The incidence rate of anxiety and depression is significantly higher in patients with inflammatory bowel diseases(IBD)than in the general population.The mechanisms underlying dextran sulfate sodium(DSS)-induced depressive-like behaviors are still unclear.We clarified that IBD mice induced by repeated administration of DSS presented depressive-like behaviors.The paraventricular thalamic nucleus(PVT)was regarded as the activated brain region by the number of c-fos-labeled neurons.RNA-sequencing analysis showed that lipocalin 2(Lcn2)was upregulated in the PVT of mice with DSS-induced depressive behaviors.Upregulating Lcn2 from neuronal activity induced dendritic spine loss and the secreted protein induced chemokine expression and subsequently contributed to microglial activation leading to blood-brain barrier permeability.Moreover,Lcn2 silencing in the PVT alleviated the DSS-induced depressive-like behaviors.The present study demonstrated that elevated Lcn2 in the PVT is a critical factor for DSS-induced depressive behaviors.

重组枯草芽孢杆菌诱导表达AiiA及酶活性鉴定

[目的]由于AiiA(Autoinducer inactivation,AiiA)蛋白能有效降解AHLs(N-acyl-homoserine,AHLs),导致病原菌由于群体淬灭(Quornm quenching,QQ)失去生存优势而抑制其致病能力;利用强启动子构建能高效表达AiiA蛋白的枯草芽孢杆菌,检验枯草芽孢杆菌中Pspac启动子表达AiiA蛋白的能力,寻求有效生物防治手段防治病原菌侵害。[方法]通过已知的aiiA基因序列和启动子Pspac序列设计引物,经搭桥PCR搭连启动子Pspac和aiiA基因,构建重组表达载体Pspac-aiiA-PHY300PLK,经酶活反应确定重组菌活性。[结果]成功克隆并搭连Pspac启动子和aiiA基因,AiiA蛋白成功在重组枯草芽孢杆菌C11中表达。经酶活检验,野生菌株和重组菌株Pspac-aiiA-C11有降解信号分子AHLs的能力,但重组菌降解能力更强。[结论]重组菌Pspac-aiiA-C11较野生菌株有更强的降解AHLs效力;要利用工程菌进行生物防治还需进一步提高工程菌表达AiiA蛋白的能力及稳定性。

红外相机安放于地面和林冠层对野生动物监测结果的影响

红外相机技术在野生动物研究中日趋普及,逐渐成为重要的生物多样性监测手段。过去的监测常局限于地面,而针对林冠层的监测较少,这对野生动物的多样性评估影响尚未可知。为此,本研究在生物多样性丰富的碧罗雪山南段,将20台红外相机分别拍摄地面层(0.5–1.5 m)和林冠层(5–10 m)配对比较,累计拍摄2,319个有效相机日,平均每对相机同步进行112.5 d的监测。监测期间共拍摄到44种野生动物(不包括鼠形啮齿类),其中兽类20种,鸟类24种;冠层和地面红外相机监测的物种相似度为29.54%;15种动物仅拍摄于林冠层,16种动物仅拍摄于地面,13种动物拍摄于两个林层。研究结果表明不同林层监测的物种组成存在显著差异,林冠层与地面层监测都具有不可替代性;不同林层红外相机的监测手段也能用于研究野生动物的空间选择和生态位分化。红外相机监测中根据目标物种的习性在相应的林层设置相机能提高物种发现率;为全面掌握区域森林生态系统野生动物的多样性,红外相机监测需要兼顾不同林层这一点需要在监测规范中明细。